The present invention relates to the field of advanced medical devices and particularly to intracorporeal devices for performing or aiding in the performance of therapeutic or diagnostic procedures. The intracorporeal devices may be guiding members such as guide wires for advancing intraluminal devices within body lumens. The intracorporeal medical devices include stent delivery catheters, balloon dilatation catheters, atherectomy catheters, electrophysiology catheters and the like.
In a typical percutaneous coronary procedure, a guiding catheter having a preformed distal tip is percutaneously introduced into a patient""s peripheral artery, e.g. femoral or brachial artery, by means of a conventional Seldinger technique and advanced therein until the distal tip of the guiding catheter is seated in the ostium of a desired coronary artery. A guide wire is first advanced by itself through the guiding catheter until the distal tip of the guide wire extends beyond the arterial location where the procedure is to be performed. Then a rapid exchange type catheter, such as described in U.S. Pat. No. 5,061,273 (Yock) whose contents are hereby incorporated by reference, is mounted onto the proximal portion of the guide wire which extends out of the proximal end of the guiding catheter which is outside of the patient. The catheter is advanced over the guide wire, while the position of the guide wire is fixed, until the operative element on the rapid exchange type catheter is disposed within the arterial location where the procedure is to be performed. After the procedure is performed, the rapid exchange type catheter may be withdrawn from the patient over the guide wire, or the guide wire may be repositioned within the coronary anatomy for an additional procedure. Of course, the procedure may also be performed with an Over The Wire (OTW) type catheter and is not limited to just Rapid Exchange (RX) type catheters.
A guide wire may also be used in conjunction with the delivery of an intracoronary stent. One method and system involves disposing a compressed or otherwise small diameter stent over an expandable member, such as a balloon, at the distal end of a catheter. The physician advances the catheter through the patient""s vascular system over a guide wire until the stent is at the desired location within a blood vessel. The expandable member on the catheter is inflated to expand the stent within the blood vessel. The dilated expandable member is then deflated and the catheter withdrawn, leaving the expanded stent within the blood vessel. Once deployed, the expandable member ensures patency of the blood vessel by holding the passageway open. This latter method and system can be used concurrently with balloon angioplasty or subsequent thereto.
Further details of guide wires and devices associated therewith for various interventional procedures can be found in, for example, U.S. Pat. No. 4,748,986 (Morrison et al.); U.S. Pat. No. 4,538,622 (Samson et al.); U.S. Pat. No. 5,135,503 (Abrams); U.S. Pat. No. 5,341,818 (Abrams et al.); and U.S. Pat. No. 5,345,945 (Hodgson,et al.), whose contents are hereby incorporated by reference.
Conventional guide wires for angioplasty, stent delivery, atherectomy, and other intravascular procedures usually have an elongate core with one or more segments near the distal end thereof that taper distally to smaller cross-sections. A flexible body, such as a helical coil or a tubular body of polymeric material, is typically disposed about and secured to at least part of the distal portion of the core. A shapeable tip, which may be the distal extremity of the core or a separate shapeable ribbon that is secured to the distal extremity of the core, extends through the flexible body and is secured to the distal end of the flexible body by soldering, brazing, or welding; or by use of an adhesive in the case of a polymeric flexible body which forms a rounded distal tip. This rounded, distal or leading tip is highly flexible so that it does not damage or perforate the vessel. The portion behind the distal tip is increasingly stiff to better support a balloon catheter or similar device.
The shapeable member or ribbon of a typical guide wire is a small diameter wire that has been flattened to a relatively constant transverse profile. Flattening of the shapeable member facilitates the shapability of the member. However, a shapeable member having a constant transverse profile or flexibility could be subject to prolapse during use. Prolapse occurs when the shapeable member gets bent back on itself inside a constrained lumen, and is difficult to straighten out with only proximal manipulation.
The present invention is generally directed to a medical device such as a guiding member for performing or aiding in the performance of a therapeutic or diagnostic procedure. In various exemplary embodiments, the present invention is directed to a guide wire or similar guiding member for the introduction and advancement of a medical device into a patient for the performance of a therapeutic or diagnostic procedure.
A guiding member embodying features of the present invention generally has a shapeable member, which extends from a distal core section and has a distal portion extending beyond the distal core section with a non-rectangular cross-sectional shape defined by width b and a height h. In one embodiment, the present invention guide wire includes a moment of inertia having a moment of inertia defined by 0.083xc3x97bxc3x97h3. Preferably, the value for the moment of inertia is defined by at least 0.1xc3x97bxc3x97h3.
The guiding member may have an elongate core with a proximal core section and a distal core section, and a flexible body disposed about and secured to at least a portion of the distal core section. The shapeable member has a distal end that is optionally secured to the distal end of the flexible body that terminates in a rounded tip. The portion of the shapeable member having the desired moment of inertia preferably has a cross-sectional shape including a non-rectangular shape, a D-shape, a triangular shape, and the like. Other non-rectangular shapes known in the art having the desired moment of inertia may also be employed.
The shapeable member may be separately formed and then joined to the distal core section in a suitable manner, or it may be formed out of a distal extremity of the core. If separately formed, the elongated shapeable member may be formed as a shaping ribbon that is mounted or attached in a suitable manner to the distal extremity of the distal core section through welding, brazing, soldering, adhesive bonding, mechanical connections, and other known mounting processes. In addition, the discrete shapeable member may by formed from round or flattened wire that is coined, rolled, or otherwise plastically deformed to a desired shape with preferably a non-rectangular cross-sectional shape.
A flexible body may be disposed about the shapeable member, preferably along its entire length and may take the form of a helical coil, polymer jacket, or the like. The distal end of the flexible body is attached to the distal end of the shapeable member and an intermediate portion of the flexible body is preferably secured to the distal core section proximal to the shapeable member. The intermediate portion of the flexible body can optionally be secured to the distal core section including the proximal end of the shapeable member.
The non-rectangular, transverse shape of the elongated shapeable member on the distal part of the guide wire changes the moment of inertia of the shapeable member as compared to one having a rectangular transverse cross-section with the same width and height, thus making the shapeable member with a non-rectangular transverse cross-section more or less flexible, depending on the non-rectangular transverse shape chosen. Furthermore, the non-rectangular transverse shape may provide for a larger or smaller profile for the shapeable member with the same strength characteristics as a shapeable member with a rectangular transverse shape.
In various embodiments, the length of the shapeable member is about, for example, 0.5 cm to about 12 cm, and preferably about 1 cm to about 10 cm. At least 50%, and preferably at least 75%, of the length of the shapeable member is optionally tapered. The taper may be straight or curved, and divergent or convergent. As to the latter, for example, the shapeable member preferably has two pairs of opposing faces that are essentially the mirror image of each other. In one embodiment, the pair of opposing faces converge toward each other while in another embodiment the pair of opposing faces diverge from each other. There may be more than one taper resulting in a shapeable member that is thicker in the middle or thinner in the middle.
Lastly, the geometry of the shapeable member may be modeled mathematically. The specific transverse shapes may be selected in keeping with the principles of the invention to achieve optimum performance for specific usage requirements. These and other advantages of the invention will become more apparent from the following detailed description of the invention when taken in conjunction with the accompanying exemplary drawings.